According to the invention, a collector is arranged within a separator and underneath said filter elements, said container constituting a collecting zone, and occupying a portion of the downwardly projected area of said filter elements, the dirty gas being arranged to flow through said container, and said container being formed from a perforated wall and being filled with bodies around which the dirty gas flows. Force-applying means are provided in association with said container to detach the dust which clings to said bodies and collects between them, the said force-applying means being operative to make an at least intermittent application of force, and the coarse dust which enters the container zone when said filter elements are cleaned periodically is broken down until it is able to be carried back to the filter elements by the dirty gas.
The present invention relates to filtering separators in particular pocket or tube filters of the kind having a lower inlet for dust-or smoke-laden gas containing extremely adherent dust particles which is directed upwards towards the filter elements, the dust which settles when the filter elements are cleaned periodically being carried back to the filter elements by this dirty gas for agglomeration purposes and a proportion of the agglomerated dust which corresponds to the quantity of dust in the incoming dirty gas and which the said gas is not capable of carrying with it to the filter elements being extracted during the periodic cleaning of the filter elements. Hereinafter, such a separator will be referred to as "of the kind described".
By means of filtering separator of the kind described, it is possible to bring about agglomeration of the very fine dust contained in the smoke-laden gas while in the suspended state and immediately before it reaches the actual filter surfaces, so that in this way the layer of dust on the filter surfaces remains permeable to the smoke-laden gas, thus preventing the resistance of the filter to flow becoming excessive. In particular this makes it possible for the filter surfaces to be cleaned in the conventional fashion by countercurrent scavenging and/or joggling.
The method described above has proved satisfactory in practice as long as the adhesiveness of the very fine dust in the dirty i.e. smoke-laden gas which is due to its large surface area compared with its small mass, does not exceed a certain level. Due to the excessive adhesiveness of such fine dust in certain types of smoke-laden gas from smelting furnaces or the like, the particles of dust which build up on one another and on and in the filter surfaces remain clinging where they are or often remain suspended on the individual filaments of the filter surfaces in small clumps when conventional cleaning methods are used, despite the agglomeration by dust feedback, which may lead to irreversible obstruction of the filter and a continual reduction in the speed of filtering and a severe rise in the resistance to flow of the filter, which would mean that the filter system would have to be expanded to an economically unreasonable size.
It is an object of the invention to make it possible to use filtering separators such as pocket or tube filters in which the filter surfaces are cleaned periodically by countercurrent scavenging and/or joggling and in which the dust which settles during the periodic cleaning is fed back to the filter surfaces by the stream of smoke-laden gas, even when smoke-laden gases containing extremely adherent fine dust is to be cleaned and large amounts of dust remain in the filtering separator when this is done.